In existing Long Term Evolution (LTE), a time-frequency resource is usually statically configured, and only uplink signals or downlink signals are transmitted in an entire network at a same time point. For example, for a time division duplex (TDD) system, all base stations in the entire network generally use a same uplink-downlink subframe configuration. In this way, as shown in FIG. 1, at a downlink time point, a signal received by any user equipment (UE) in a cell is interfered with by a downlink signal sent by another base station. Alternatively, as shown in FIG. 2, at an uplink time point, an uplink signal received by any base station in a network is interfered with by an uplink signal sent by UE in another cell. In FIG. 1 and FIG. 2, base stations use a same uplink-downlink subframe configuration, D means that a downlink signal is transmitted in this timeslot, and U means that an uplink signal is transmitted in this timeslot. Similarly, the same can be said for a frequency division duplex (FDD) system.
However, due to the static resource configuration manner, resource allocation cannot be flexibly adjusted according to a service volume. Therefore, for the TDD system, dynamic TDD becomes a current research focus of the 3rd Generation Partnership Project (3GPP). In the dynamic TDD, each base station in the network is allowed to flexibly adjust an uplink-downlink timeslot configuration. However, at a same time point, the following case may occur. For adjacent cells, a downlink signal is transmitted in one cell and an uplink signal is transmitted in the other cell. As shown in FIG. 3, signal transmission directions of two adjacent base stations are different in the fourth timeslot. In this case, in addition to base station-to-UE interference and UE-to-base station interference in the existing LTE system, base station-to-base station interference (interference I in FIG. 3) and UE-to-UE interference (interference II in FIG. 3) are generated in the network. For the FDD system, some uplink resources may be converted into downlink resources, that is, a downlink signal is sent on an uplink frequency band. In this way, spectrum utilization of the network is greatly improved. This may be implemented using time division, that is, as shown in FIG. 4, a base station sends a downlink signal in some timeslots on an uplink frequency band (designated as FDD UL in FIG. 4), and UE still sends an uplink signal in other timeslots on the uplink frequency band. Alternatively, this may be implemented using frequency division. As shown in FIG. 5, an uplink frequency band (designated as FDD UL in FIG. 5) resource is divided into two parts. One part is used by UE to send an uplink signal, and the other part is used by a base station to send a downlink signal. Similar to the TDD system, at a same time point, the following case may occur. For adjacent cells, a downlink signal is transmitted in one cell and an uplink signal is transmitted in the other cell. Therefore, in addition to base station-to-UE interference and UE-to-base station interference in a conventional wireless communications system, base station-to-base station interference is generated in the network.
For the two types of newly generated interference, the 3GPP sets up a related project to study how to further enhance management of interference between an uplink signal and a downlink signal. A current solution is as follows. Edge physical resource blocks (PRBs) may be reserved for transmitting a physical uplink control channel (PUCCH), and scheduling limits are used to disallow a physical downlink shared channel (PDSCH) to be transmitted on these PRBs. However, these scheduling limits can avoid PDSCH transmission only on some PRBs. To guarantee backward compatibility, downlink control information such as a physical downlink control channel (PDCCH) is still transmitted on edge PRBs. As a result, there is still interference between the downlink control information and the PUCCH.
Therefore, how to provide a new interference suppression method to suppress interference between an uplink signal and a downlink signal becomes an urgent problem to be resolved currently.